Ford Boss 302 Engine Build - Build A Better Boss - Tech

A Legendary 5.0L Upgrade

Richard Holdener

October 21, 2010

In stepping things up, we decided to utilize the same short-block, though we did have to disassemble the motor to have valve reliefs cut into the pistons for our more aggressive cam profile(s). Additional upgrades included replacing the stock Boss 302 pan and windage tray with a much-improved version from Moroso. The Moroso oiling system included a full-length, louvered windage tray matched to a deep-sump oil pan and matching pick up. The oiling system upgrades were critical for our high-rpm needs.

Speaking of high rpm, the mild stock Boss 302 stick from Schneider cams was not going to get the job done, so we initially swapped in a roller profile from Comp Cams that we happened to have from a previous project. Though not designed specifically for our CHI-headed 302, the Comp roller worked well and allowed us to exceed the 500hp mark. The Comp roller cam checked in with a 0.731/0.716 lift split (with 1.73:1 rocker), a 252/264 duration split at 0.050-inch, and a tight 107-degree lobe separation angle.

Since we were looking to maximize power production and the short-block was already broken in from its original running in stock Boss 302 configuration, we took the liberty of running ultra-light synthetic oil. Lucas Oil supplied some 5W Pro Stock oil designed for high-rpm race engines with good oiling systems. We also threw on a Holley 950 HP carb, and tried a few different carb spacers, as well as lash adjustments on the combination, with a lash of 0.010-inch on both the intake and exhaust working best with the Comp cam. Once we had emptied our bag of tricks, we were eventually rewarded with peak power numbers of 520 hp at 7,200 rpm and 399 lb-ft at 5,700 rpm. Not bad considering we were dealing with a static compression ratio near 10.5:1.

Having easily surpassed the 372 hp put down by the stock Boss 302 and officially reached our goal of topping the 500hp mark, you'd think we'd call it a day and head down to the local tavern. Not quite. We swapped out the original Comp cam and installed the stick from Cam Research Corp (www.cam
researchcorp.com) in Englewood, Colorado. The Cam Research Corp roller cam offered a similar 0.721/0.724 lift split, a slightly smaller 245/249-degree duration split, and an equally tight 102-degree lobe separation angle.

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On the first pull we knew we had a winner, as the Cam Research cam not only produced higher peak torque numbers of 418 lb-ft, but also managed to bump our peak power up to 542 hp. A piston-to-valve clearance issue required we run the cam a minimum of 3 degrees retarded, but this didn't seem to hurt power production in our tested rev range. Though slightly smaller in specs, the Cam Research Corp cam offered both more average and peak power numbers than the larger Comp cam (admittedly not specifically made for this application). Having exceeded 540 hp with our CHI-headed 302, we couldn't help but wonder how much cam and compression would be required to top the 600hp mark? But that is another dyno story for another day.